Optimized graph traversal

ABSTRACT

Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for optimized graph traversal are disclosed. In one aspect, a method includes the actions of receiving a given phrase that is input through a user interface by a digital component provider. The actions further include determining an entity that is being referred to by the given phrase. The actions further include identifying properties of the entity. The actions further include selecting a subset of the properties that were identified for the entity. The actions further include identifying additional phrases. The actions further include updating the user interface to present at least some of the additional phrases with programmatic controls that assign one or more of the additional phrase as distribution criteria for digital components of the digital component provider in response to activation of the programmatic controls.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. application Ser.No. 15/439,456, filed Feb. 22, 2017, which is incorporated by reference

FIELD

This application relates to data access and data processing.

BACKGROUND

A database is a collection of organized data. A user may access adatabase to identify information related to a given piece of data. Forexample, a user may access a database to identify different types offruits or brands of automobiles.

SUMMARY

To identify additional phrases (e.g., one or more words) that aresemantically related to a given phrase, a user (e.g., digital componentprovider) may submit the given phrase to a system that is configured totraverse a knowledge graph. The knowledge graph provides structured anddetailed information about various entities (e.g., specific people,places, things, or topics). The knowledge graph uniquely identifies eachdifferent entity using a node and a unique entity identifier that isassigned to the node. The knowledge graph links nodes using relationshiplinks that specify the specific relationship between the nodes. Forexample, assume that movie titled “Movie A” is directed by “Director 1.”In this example, the node in the knowledge graph assigned to “Movie A,”would be linked to the node assigned to “Director 1,” and the link (ormultiple links) between these nodes would have one or more labels thatspecify that “Movie A” has a relationship of “directed by” to “Director1,” and that “Director 1” has the relationship of “directed” with “MovieA.” The collection of nodes and links in the knowledge graph enables theidentification of related concepts, which may not otherwise be apparent,by traversing the links and/or nodes of the knowledge graph.

The knowledge graph is vast and traversing more than one level away froma topic is computationally expensive. To reduce the load on the systemin traversing the knowledge graph, the system may identify relationshipsthat the given phrase has with other phrases and select for evaluationonly those relationships to the given phrase that are likely to lead tophrases that are more closely related or have higher phrase actionscores (e.g., interaction rates, or post-interaction activity rates). Byselecting for evaluation only those relationships to the given phrasethat are likely to reveal phrases that have high phrase action scores,the system reduces the number of knowledge graph paths for the system totraverse, and thus identifies phrases that are related to and/or havehigh phrase action scores faster and with fewer computing resources thantraversing all relationships that are specified by links between thegiven phrase and other phrases. As such, the traversal of the knowledgegraph is optimized (e.g., improved) so that the knowledge graph can beused in a real-time interactive environment to provide real-timeinformation in response to user input, thereby improving theusability/functionality of the knowledge graph.

According to an innovative aspect of the subject matter described inthis application, a method for persisting state of a streamingapplication includes the actions of receiving a given phrase that isinput through a user interface by a digital component provider;determining an entity that is being referred to by the given phrase byaccessing a knowledge graph comprising nodes that each uniquely identifydifferent entities, and identifying a particular node that uniquelyidentifies the entity being referred to by the given phrase, where thenodes of the knowledge graph are connected by edges that representrelationships between connected nodes; identifying properties of theentity by accessing other nodes that are connected the particular nodethe entity; selecting a subset of the properties that were identifiedfor the entity identifying additional phrases by accessing the knowledgegraph using the subset of properties that were identified for theentity; and updating the user interface to present at least some of theadditional phrases with programmatic controls that assign one or more ofthe additional phrase as distribution criteria for digital components ofthe digital component provider in response to activation of theprogrammatic controls.

These and other implementations can each optionally include one or moreof the following features. The actions further include reducing a numberof accesses to the knowledge graph by the knowledge graph traverser whenidentifying the additional phrases. The actions further includeidentifying, from among the additional phrases, one or more phrases thathave a higher performance characteristic than other phrases among theadditional phrases by accessing phrase action scores for the identifiedadditional phrases, comparing the phrase action scores to each other,identifying one or more of the phrase action scores having highestvalues based on the comparison, and selecting the one or more additionalphrases having the phrase action scores having the highest values. Theactions further include selecting the subset of the propertiesassociated with the entity using a selection model continuously trainedusing machine learning. The actions further include initially trainingthe selection model using selection model training data includingphrases associated with previous search queries submitted by users,digital component selection data associated with the previous searchqueries, entities associated with the phrases, and properties associatedwith the entities. Additional identified phrases comprise a minimumspanning tree among the entity.

Other embodiments of this implementation include corresponding systems,apparatus, and computer programs recorded on computer storage devices,each configured to perform the operations of the methods.

The subject matter described in this specification may have one or moreof the following advantages. A user can identify phrases that arerelevant to a given phrase by accessing the knowledge graph. The systemmay limit the traversing of the knowledge graph to reduce computerprocessing requirements.

The details of one or more embodiments of the subject matter describedin this specification are set forth in the accompanying drawings and thedescription below. Other features, aspects, and advantages of thesubject matter will become apparent from the description, the drawings,and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example system for phrase identifying using aknowledge graph.

FIG. 2 illustrates example an example knowledge graph.

FIG. 3 illustrates an example process for phrase identifying using aknowledge graph.

FIG. 4 illustrates an example of a computing device and a mobilecomputing device.

DETAILED DESCRIPTION

FIG. 1 illustrates an example system 100 for phrase evaluation using aknowledge graph 105. Briefly, and as described in more detail below, theuser 110 (e.g., a digital component provider) submits a given phrase 115through computing device 120. The computing device 120 transmits thegiven phrase 115 to the server 125. The server 125 accesses theknowledge graph 105 using the given phrase 115 and traverses nodes/linksof the knowledge graph that are connected to the given phrase. Thetraversal of the nodes/links of the knowledge graph reveals expansionphrases 130 (e.g., other phrases that are related to the given phrase bybeing connected to the given phrase by a particular relationship linkand/or having a phrase action score that meets a pre-specifiedthreshold). The server 125 then provides a list of the expansion phrases130 to the computing device 120. The user 110 can interact with one ormore of the expansion phrases, groups of expansion phrases, or selectioncontrols corresponding to expansion phrases to assign expansion phrasesas distribution criteria for one or more digital components (e.g., videofiles, audio files, images, text, or other content including content inthe form of advertisements).

In more detail and following the example illustrated in FIG. 1, assumethat the user 110 enters the phrase 115 “youthful and fidgety” into aphrase expansion tool (e.g., a script and hardware components thatoperate to identify expansion phrases) running on the server 125. Thephrase expansion tool generates a user interface through the userinterface generator 132. The user interface generator 132 provides auser interface that is displayed on the computing device 120 andreceives input from the user 110. The phrase expansion tool isconfigured to identify expansion phrases that are related to the givenphrase 115 through links in the knowledge graph, and/or that have atleast a specified phrase action score. Phrases that have at least aspecified phrase action score are those phrases that have resulted in atleast a minimum level of end user interaction with digital componentsthat were distributed using the phrases. In some implementations, theminimum level of end user interaction can be specified using a thresholdphrase action score.

The server 125 receives the given phrase 115 through the user interface132 and provides the given phrase 115 to the knowledge graph traverser135. The knowledge graph traverser 135 is configured to access and/ortraverse the knowledge graph 105. The knowledge graph 105 and othercomponents of server 125 may be located on the server 125 or may bedistributed across multiple servers that include server 125. Themultiple servers and server 125 may be accessible through network 145.In other words, the multiple servers and server 125 may be located inthe cloud. During the initial access of the knowledge graph 105, theknowledge graph filter 140 may not yet be configured for the givenphrase 115. Instead, the knowledge graph traverser 135 may access theknowledge graph directly.

Briefly turning to FIG. 2, which illustrates an example of the knowledgegraph 200. The knowledge graph 200 may be similar to the knowledge graph105 in FIG. 1. In general, the knowledge graph 200 is a collection ofdata (e.g., nodes) representing entities and relationships (e.g.,labeled links) between entities (e.g., represented by the nodes). Thedata is logically described and illustrated as a graph, in which eachdistinct entity is represented by a respective node and eachrelationship between a pair of entities is represented by an edge (orlink) between the nodes. Each edge specifies a relationship (e.g., inthe form of a label) and the existence of the edge represents that thespecified relationship exists between the nodes connected by the edge.For example, if node 202 represents the person Christine Wilson, node204 represents a television show Admiral Clinic, and edge 206 specifiesthe relationship “is an actress in,” then having the edge 206 connectthe nodes 202 and 204 in the direction from node 202 to node 204 (e.g.,unidirectional) in the graph represents the fact that Christine Wilsonis an actress in Admiral Clinic. Other connections for node 202 mayexist in the knowledge graph 200 that are not related to being anactress. For example, node 202 may be connected to a node representingJack Wilson. Node 202 and the node representing Jack Wilson may beconnected by an edge with the relationship “is married to.” In thisexample, the edge with the relationship “is married to” may be abidirectional edge since Jack Wilson is married to Christine Wilson andChristine Wilson is married to Jack Wilson.

The knowledge graph 200 can be represented by any of a variety ofphysical data structures. For example, a knowledge graph can berepresented by triples that each represent two entities in order and arelationship from the first to the second entity; for example,[Christine Wilson, Admiral Clinic, is an actress in], or [ChristineWilson, is an actress in, Admiral Clinic], are alternative ways ofrepresenting the same fact. Each entity and each relationship can be andgenerally will be included in multiple triples. As noted above, eachentity in the knowledge graph has a corresponding entity identifier thatuniquely identifies the entity relative to other entities, even if thesame phrase describes two different entities. For example, assume thattwo entities are textually identified using the phrase “jaguar.” In thisexample, the entity node in the knowledge graph representing the carhaving the name Jaguar can have the entity identifier “12345,” whereasthe entity node representing the animal jaguar can have the entityidentifier “54321,” thereby differentiating these two entities havingthe same name. In some implementations, the entity identifier ratherthan, or in addition to, the entity name can be included in the tripletsdiscussed above (or other data structures representing the knowledgegraph).

In some implementations, each entity can be stored as a node once, as arecord or an object, for example, and linked through a linked list datastructure to all the relationships the entity has and all the otherentities to which the entity is related. More specifically, theknowledge graph 200 can be stored as an adjacency list in which theadjacency information includes relationship information. It is generallyadvantageous to represent each distinct entity and each distinctrelationship with a unique identifier.

The entities represented by the knowledge graph 200 need not be tangiblethings or specific people. The entities can include particular people,places, things, artistic works, concepts, events, or other types ofentities. Thus, a knowledge graph can include data definingrelationships between people, e.g., co-stars in a movie; data definingrelationships between people and things, e.g., a particular singerrecorded a particular song; data defining relationships between placesand things, e.g., a particular type of wine comes from a particulargeographic location; data defining relationships between people andplaces, e.g., a particular person was born in a particular city; andother kinds of relationships between entities. As another example inknowledge graph 200, node 208 that represents television producerAmerican Studios is connected to node 210 that represents televisionshow Youthful and Fidgety. Node 208 and 210 are connected by edge 212that corresponds to the relationship “is a producer of.” Based on theconnection from node 208 to node 210 using edge 212, American Studios isa producer of Youthful and Fidgety.

In some implementations, each node has a type based on the kind ofentity the node represents; and the types can each have a schemaspecifying the kinds of data that can be maintained about entitiesrepresented by nodes of the type and how the data should be stored. So,for example, a node of a type for representing a person could have aschema defining fields for information such as birth date, birth place,and so on. Such information can be represented by fields in atype-specific data structure, or by triples that look likenode-relationship-node triples, e.g., [person identifier, was born on,date], or in any other convenient predefined way. Alternatively, some orall of the information specified by a type schema can be represented bylinks to nodes in the knowledge graph; for example, [one personidentifier, child of, another person identifier], where the other personidentifier is a node in the graph.

As an example in knowledge graph 200, node 214 that represents ElizabethAnderson may include data indicating that she was born in 1970 inSpringfield. Alternatively, node 214 may be connected to a node thatrepresents the year 1970 and a node that represents the locationSpringfield. Node 214 may be connected to the node that represents theyear 1970 through an edge that corresponds to “was born in.” Node 214may also be connected to the node the represents the locationSpringfield through an edge that also corresponds to “was born in.” Assuch, when the server 125 traverses the knowledge graph from the node214 using the relationship “was born in,” the server 125 arrives at bothof the nodes 215 a (representing Springfield, Ohio) and 215 b(representing 1970). The server 125 can aggregate the information fromeach of the nodes that link to the node 214 by the relationship “wasborn in” to generate the fact that Elizabeth Anderson was born inSpringfield, Ohio in 1970. As the number of nodes having a samerelationship to a particular node (or set of nodes) increases, thecomputational complexity of traversing the knowledge graph to identifyinformation increases, which can lead to slow responsiveness and limitthe ability to use the knowledge graph in real-time interactiveenvironments. Further, as the number (or types) of differentrelationships that are evaluated increases, this will further complicatethe retrieval of information from the knowledge graph. Due to the sheervolume of information included in the knowledge graph and the timeconstraints for accessing/processing this information to provide a realtime interactive online application, the use of computing devices isrequired to effectively utilize the knowledge graph.

Based on the above description, it is apparent that traversing theknowledge graph 200 is a complex and computational expensive operationas the knowledge graph 200 only represents a small portion of a largerknowledge graph that currently exists. While the node 210 representingthe television show Youthful and Fidgety may only have about eleven inthe example knowledge graph 200, in reality, node 210 may have hundreds,thousands, or millions of connections. As such, techniques are needed tointelligently identify which portions of the knowledge graph should betraversed and/or evaluated for purposes of identifying information(e.g., expansion phrases) in response to a request for information(e.g., submission of a given phrase). The goal of the knowledge graphfilter 140 is to reduce the number of nodes and edges that the knowledgegraph traverser 135 has to traverse to identify the expansion phrases130 that are returned to a user 110 that submits the given phrase 115.Doing so will decrease the time spent, power used, memory used, andprocessing capability used by the knowledge graph traverser 135 inidentifying the expansion phrases 130 that are related to phrase 115. Inturn, the knowledge graph filter 140 enables the knowledge graph toselect and return expansion phrases in the context of a real-timeinteractive environment, which enables a user 110 to identify and selectvarious new/different phrases that are used to distribute digitalcomponents provided by the user 110.

Returning to the knowledge graph traverser 135 accessing the knowledgegraph 105 or 200 directly, the knowledge graph traverser 135 accessesthe knowledge graph 105 at node 210 that corresponds to the phraseyouthful and fidgety. As illustrated in the knowledge graph 200, node210 is connected to node 216 through edge 218, node 220 through edge222, node 224 through edge 226, node 228, node 214 through edge 230,node 208 through edge 212, node 232 through 234, node 236 through edge238, node 202 through edge 240, node 242 through edge 244, and node 246.Each of these edges represents a potential property of the node 210 thatcorresponds to the phrase youthful and fidgety.

The knowledge graph traverser 135 provides the nodes and edges connectedto the node 210 to the property selector 150. The property selector 150is configured to identify those connected nodes that correspond toproperties and to select a subset of those properties that are mostlikely to lead to phrases with higher performance characteristics. To dothat, the property selector 150 may apply one or more selection models.The property selector may choose the selection model based on the phrase115 or the user 110 or both. For example, if the user 110 is mediacompany and the phrase 115 youthful and fidgety, the property selectormay select the properties of actors and writers. The property selector150 may select actors and writers by examining the edges that connect tothe node 210. For example, the properties for node 210 include “is anactor/actress in” from edges 244, 240, 238, and 234, “is a producer of”from edge 212, and “is a writer of” from edge 214. The property selector150 may also determine that the node 210 of “youthful and fidgety” is atelevision award winner, a television show, and a soap opera based onnodes 224, 220, and 216, respectively. The knowledge graph 200 may alsoadditional nodes connected to nodes 224, 220, and 216 that representother television shows. Each of those television show nodes may havewriters, directors, producers, actors/actresses, etc. (e.g., asdetermined by relationship edges connecting the nodes). The propertyselector 150 may select the properties of actor/actress and writerbecause those are likely to lead to the phrases with the highestperformance properties. This is because end users entering searchqueries may be more likely to enter names of actor/actress and writerinstead of producers or directors.

To assist the property selector 150 in identifying the property selector150 may access one or more selection models 155. Before processingphrases, the property selector 150 may access selection model trainingdata 160. The selection model training data 160 may include data relatedto previous search queries, content item selection data of thoseprevious search queries, entities with the phrases, and properties ofthe entities and with the phrases. The property selector 150 may useneural networks and machine learning to generate the models 155. Theserver 125 may receive additional training data as more end users entersearch queries. The server 125 may store the training data in theselection model training data 160 and the property selector 150 mayupdate the selection models 155. Each selection model may be generatedfor a type of phrase and digital component provider. For example,phrases related to related to television shows may have a differentmodel then phrases related to food.

Using the properties of “is an actor/actress in” and “is a writer of,”the knowledge graph traverser 135 may then access the knowledge graph toidentify additional phrases along those properties of the knowledgegraph 105. As illustrated in FIG. 2, the knowledge graph traverser 135accesses nodes 242, 202, 236, 232, and 214. The knowledge graph filter140 filters out the nodes 208, 228, 224, 220, 216, and 246. The reducesthe computational cost of accessing the knowledge graph 200 by over halfbecause the knowledge graph traverser 135 does not traverse down thenodes 208, 228, 224, 220, 216, and 246. The knowledge graph traverser135 identifies nodes that have similar relationships to the nodes 242,202, 236, 232, and 214 that those nodes have to the original phrase node210. In particular, the knowledge graph traverser 135 identifies nodes248, 250, 252, 254, 256, 258, 260, 262, 264, 266, 268, 270, and 272.Each of these nodes has either “is an actor/actress in” or “is a writerof” relationship with the nodes connected to the node 210. To keep thesize of the knowledge graph 200 from being too large for the page somenodes, such as nodes 248, 250, 246, 228, 260, 262, 264, and 266, arerepresented in abbreviated form where “---” represents some value andthe connecting edge includes a relationship. The actual value has beenremoved from the representation of knowledge graph 200.

The knowledge graph traverser 135 provides the data from nodes 248, 250,252, 254, 256, 258, 260, 262, 264, 266, 268, 270, and 272 to the phraseselector 165. The data in these nodes are the relevant phrasesidentified by the knowledge graph traverser 135. The phrase selector 165may be configured to return a particular number of phrases that have thehighest phrase action scores (which may be pre-calculated by a remoteserver and/or simply accessed from a data store that stores an indexbetween phrases and their corresponding phrase action scores). Forexample, of the phrases received from the knowledge graph traverser 135,the phrase selector 165 may return the seven phrases with the highestperformance characteristics. The phrase selector 165 may also beconfigured to return a particular percentage of the phrases with thehighest performance characteristics. In some implementations, the phraseselector 165 may be configured to return the phrases with performancecharacteristics that are higher than the performance characteristics ofthe phrase 115.

To identify the phrases with the highest performance characteristics,the phrase selector 165 accesses the phrase performance history 170. Thephrase performance history 170 may include data related to the phraseaction scores for all the phrases of search queries and displayeddigital components. In this example, the phrases with the highestperformance characteristics are Running Alive, Eastplanet, AdmiralClinic, Familiar Objects, Older, Bug Man, and Blue is the New White.Therefore, the server 125 returns the expansion phrases 130. The user110 may choose to bid on those phrases so that the user's 110 digitalcomponents may be displayed when an end user enters a search queryrelated to one of these phrases.

In some implementations, the knowledge graph filter 140 may accessdifferent models in the selection models 155. In the example shown inFIG. 1, the actors and writer who correspond to nodes 242, 202, 236,232, and 214 may not be equals in the sense that some of the actors andwriters may be more popular than others. In this regard, a model may beable to filter out nodes that have the same or similar properties asother nodes in favor of the nodes that is the more popular, in terms ofmore search queries. For example, the knowledge graph filter 140 mayfilter out nodes 242, 236, and 232 because those nodes have a commonproperty with more popular node 202. For example, Bob Johnson, AliceSmith, David Brown, and Christine Wilson are all actors or actresses inYouthful and Fidgety. Christine Wilson may be the most popular of thefour, so the knowledge graph filter 140 filters out Bob Johnson, AliceSmith, David Brown. The knowledge graph filter 140 may not filter outnode 214 because node 214 corresponds to the only writer for node 210and writer was previously identified as popular. The knowledge graphfilter 140 effectively reduce the nodes that connect to node 210 to onlynode 202 and node 214 therefore reducing the load on the processor andmemory required to traverse the knowledge graph 105 to the next level.

In some implementations, the server 125 may use the knowledge graph 105to identify phrases that may be similar to phrase 115 by onlyidentifying different entities that correspond to the phrase 115. In theexample knowledge graph 200, the server may identify that node 210corresponds to the entities of soap opera at node 216, television showat node 220, and television award winner at node 224. Each of thosenodes 216, 220, and 224 may connect to other nodes that are also soapoperas, television shows, television award winners, or any combinationof the three. Although not illustrated in knowledge graph node 256corresponds to both a soap opera and television show, so that node 256includes a connection to nodes 216 and 220. The knowledge graphtraverser 135 identifies the nodes that connect to each of the entitiesof nodes 216, 220, and 224 and identifies those nodes that connect tothe entity nodes. The phrase selector 165 then identifies theperformance characteristic for each of the phrases of the nodesconnected to nodes 216, 220, and 224. The phrase selector 165 may thenidentify the phrases and/or the entities that correspond to theperformance characteristics. For example, the phrase selector 165 mayidentify that phrases of entities that correspond to the soap operaentity perform better than those of the television show entity or thetelevision award winner entity.

In some implementations, the phrase selector 165 may utilize a minimumspanning tree to identify phrases. The phrase selector 165 identifiesthose phrases within the related entities that have the highestperformance factors. For example, the phrase selector may identify theminimum number of nodes that span the three nodes 216, 220, and 224.There may be a node that connects to all the nodes 216, 220, and 224.The performance factors may be compared to other groups of nodes thatconnect to 216, 220, and 224 to identify the smallest group of phraseswith the highest performance factors per node.

In some implementations, the user 110 may provide multiple phrases tothe system 125 and request that the system group the phrases intodifferent groups. The system accesses the knowledge graph to identifydifferent entities that each of the phrases belongs to and groups thephrases accordingly. In some instances, the system 125 may identify toomany groups. In this case, the user 110 may request that the system 125classify the phrases into fewer groups. The system may have to traverseadditional levels of the knowledge graph to identify additional groupsthat may be used to classify the received phrases.

Once the system 125 identifies the expansion phrases 130 requested bythe user 110 may allocate additional resources to those expansionphrases 130. Because the expansion phrases 130 area already identifiedas high ranking, the user 110 may divert more resources towards thosephrases in order to present digital components to end users who enterrelated search queries into a search engine.

FIG. 3 illustrates an example process 300 for phrase identifying using aknowledge graph. In general, the process 300 accesses a knowledge graphto identify phrases that are related to a received phrase. The process300 filters the knowledge graph so that the process 300 does notnecessarily have to traverse all paths related to the received phrase.The process selects phrases that are likely to have high performancecharacteristics, so that other potential expansion phrases (andpotentially corresponding relationships) can be ignored (e.g., notevaluated). The process 300 will be described as being performed by acomputer system comprising one or more computers, for example, thesystem 100 as shown in FIG. 1.

The system receives a given phrase that is input through a userinterface by a digital component provider (310). In someimplementations, the system receives data identifying a user associatedwith the phrase. For example, the system may receive the phrase “swordfighter” and the user Videogame Company. In this instance, the systemmay identify phrases that may be particularly relevant to the userVideogame Company.

The system determines an entity that is being referred to by the givenphrase by accessing a knowledge graph comprising nodes that eachuniquely identify different entities, and identifying a particular nodethat uniquely identifies the entity being referred to by the givenphrase, wherein the nodes of the knowledge graph are connected by edgesthat represent relationships between connected nodes (320). The entitymay be thought of as a type or category that represents the phrase.Following the example from above, the system accesses the nodeassociated with the phrase “sword fighter.” The system access the nodesconnected to the sword fighter node. Some of the nodes and edges mayindicates “published in 2010,” “is an action game,” “played on gamesystem” and “created by Gamer Game.” The system may select the entityfor “sword fighter” as “game system” because that entity may lead toother phrase s that are more closely related to “sword fighter” in thecontext of the user Videogame Company.

The system identifies properties of the entity by accessing other nodesthat are connected the particular node the entity (330). In someimplementations, the system may access nodes that are two levels fromthe entity. For example, nodes that are one level away from the entity“game system” may include other video games for the game system such as“Football Bowl,” “Guitar Player,” and “Gun Shooter.” Each of the gamesmay include other relationships such as “is in the genre.” The gameFootball Bowl is in the genre sports games. The game Guitar Player is inthe genre music games. The game Gun Shooter is in the genre actiongames. In this instance the three properties may be sports games, musicgames, and action games.

The system selects a subset of the properties that were identified forthe entity (340). In some implementations, the system reduces the numberof phrases by applying a model. The model may be specific to the type ofuser. In this instance, the user is a video game publisher. Based onprevious data video game publishes may be interested in learning aboutsimilar games for consoles that they produce games for. The system mayidentify the genre of action games as it is related to the originalphrase of sword fighter. By reduction the number of properties, thesystem reduces a number of accesses the system makes to the knowledgegraph. Reducing the number of accesses improves the search speech andallows other processes running on the system to access larger amounts ofprocessing power and memory because the system uses fewer resourcestraversing the knowledge graph.

In some implementations, the system trains the models using trainingdata and machine learning. The training data may be related to theproperties and entities that are typically important to different typesof users. Game console makers may be interested in games for that areproduced for their console. Television show producers may be interestedin other television shows that have actors and writers that are the sameas some of their popular shows and that are on the television network.The training data may be updated as more users select phrases that thesystem outputs. With the updated training data, the system may usemachine learning to update the models.

The system identifies additional phrases by accessing the knowledgegraph using the subset of properties that were identified for the entity(350). Continuing with the action game genre example, the systemidentifies phrases that where the same property of action game. Thesystem may identify “Space Explorer,” “Jungle Fighter,” and “WaterShooter” as other phrases that belong to the action game genre. Thesystem may also determine that these games are available the video gameconsole “Game System.” Because the user is accessing the system toidentify phrases for bidding on to display digital components, theconsole maker may not want to bid on games for other game systems. Thesystem may also select from the identified phrases to identify thosephrases that have higher performance characteristics as the otherphrases. The system may compare the performance characteristics of theidentified phrases to the original phrase and select the phrases withperformance characteristics greater than the original phrase. Someexamples of performance characteristics include phrase action scores.The system he user interface to present at least some of the additionalphrases with programmatic controls that assign one or more of theadditional phrase as distribution criteria for digital components of thedigital component provider in response to activation of the programmaticcontrols (360).

FIG. 4 shows an example of a computing device 400 and a mobile computingdevice 450 that can be used to implement the techniques described here.The computing device 400 is intended to represent various forms ofdigital computers, such as laptops, desktops, workstations, personaldigital assistants, servers, blade servers, mainframes, and otherappropriate computers. The mobile computing device 450 is intended torepresent various forms of mobile devices, such as personal digitalassistants, cellular telephones, smart-phones, and other similarcomputing devices. The components shown here, their connections andrelationships, and their functions, are meant to be examples only, andare not meant to be limiting.

The computing device 400 includes a processor 402, a memory 404, astorage device 406, a high-speed interface 408 connecting to the memory404 and multiple high-speed expansion ports 410, and a low-speedinterface 412 connecting to a low-speed expansion port 414 and thestorage device 406. Each of the processor 402, the memory 404, thestorage device 406, the high-speed interface 408, the high-speedexpansion ports 410, and the low-speed interface 412, are interconnectedusing various busses, and may be mounted on a common motherboard or inother manners as appropriate. The processor 402 can process instructionsfor execution within the computing device 400, including instructionsstored in the memory 404 or on the storage device 406 to displaygraphical information for a GUI on an external input/output device, suchas a display 416 coupled to the high-speed interface 408. In otherimplementations, multiple processors and/or multiple buses may be used,as appropriate, along with multiple memories and types of memory. Also,multiple computing devices may be connected, with each device providingportions of the necessary operations (e.g., as a server bank, a group ofblade servers, or a multi-processor system).

The memory 404 stores information within the computing device 400. Insome implementations, the memory 404 is a volatile memory unit or units.In some implementations, the memory 404 is a non-volatile memory unit orunits. The memory 404 may also be another form of computer-readablemedium, such as a magnetic or optical disk.

The storage device 406 is capable of providing mass storage for thecomputing device 400. In some implementations, the storage device 406may be or contain a computer-readable medium, such as a floppy diskdevice, a hard disk device, an optical disk device, or a tape device, aflash memory or other similar solid state memory device, or an array ofdevices, including devices in a storage area network or otherconfigurations. Instructions can be stored in an information carrier.The instructions, when executed by one or more processing devices (forexample, processor 402), perform one or more methods, such as thosedescribed above. The instructions can also be stored by one or morestorage devices such as computer- or machine-readable mediums (forexample, the memory 404, the storage device 406, or memory on theprocessor 402).

The high-speed interface 408 manages bandwidth-intensive operations forthe computing device 400, while the low-speed interface 412 manageslower bandwidth-intensive operations. Such allocation of functions is anexample only. In some implementations, the high-speed interface 408 iscoupled to the memory 404, the display 416 (e.g., through a graphicsprocessor or accelerator), and to the high-speed expansion ports 410,which may accept various expansion cards. In the implementation, thelow-speed interface 412 is coupled to the storage device 406 and thelow-speed expansion port 414. The low-speed expansion port 414, whichmay include various communication ports (e.g., USB, Bluetooth, Ethernet,wireless Ethernet) may be coupled to one or more input/output devices,such as a keyboard, a pointing device, a scanner, or a networking devicesuch as a switch or router, e.g., through a network adapter.

The computing device 400 may be implemented in a number of differentforms, as shown in the figure. For example, it may be implemented as astandard server 420, or multiple times in a group of such servers. Inaddition, it may be implemented in a personal computer such as a laptopcomputer 422. It may also be implemented as part of a rack server system424. Alternatively, components from the computing device 400 may becombined with other components in a mobile device, such as a mobilecomputing device 450. Each of such devices may contain one or more ofthe computing device 400 and the mobile computing device 450, and anentire system may be made up of multiple computing devices communicatingwith each other.

The mobile computing device 450 includes a processor 452, a memory 464,an input/output device such as a display 454, a communication interface466, and a transceiver 468, among other components. The mobile computingdevice 450 may also be provided with a storage device, such as amicro-drive or other device, to provide additional storage. Each of theprocessor 452, the memory 464, the display 454, the communicationinterface 466, and the transceiver 468, are interconnected using variousbuses, and several of the components may be mounted on a commonmotherboard or in other manners as appropriate.

The processor 452 can execute instructions within the mobile computingdevice 450, including instructions stored in the memory 464. Theprocessor 452 may be implemented as a chipset of chips that includeseparate and multiple analog and digital processors. The processor 452may provide, for example, for coordination of the other components ofthe mobile computing device 450, such as control of user interfaces,applications run by the mobile computing device 450, and wirelesscommunication by the mobile computing device 450.

The processor 452 may communicate with a user through a controlinterface 458 and a display interface 456 coupled to the display 454.The display 454 may be, for example, a TFT (Thin-Film-Transistor LiquidCrystal Display) display or an OLED (Organic Light Emitting Diode)display, or other appropriate display technology. The display interface456 may comprise appropriate circuitry for driving the display 454 topresent graphical and other information to a user. The control interface458 may receive commands from a user and convert them for submission tothe processor 452. In addition, an external interface 462 may providecommunication with the processor 452, so as to enable near areacommunication of the mobile computing device 450 with other devices. Theexternal interface 462 may provide, for example, for wired communicationin some implementations, or for wireless communication in otherimplementations, and multiple interfaces may also be used.

The memory 464 stores information within the mobile computing device450. The memory 464 can be implemented as one or more of acomputer-readable medium or media, a volatile memory unit or units, or anon-volatile memory unit or units. An expansion memory 474 may also beprovided and connected to the mobile computing device 450 through anexpansion interface 472, which may include, for example, a SIMM (SingleIn Line Memory Module) card interface. The expansion memory 474 mayprovide extra storage space for the mobile computing device 450, or mayalso store applications or other information for the mobile computingdevice 450. Specifically, the expansion memory 474 may includeinstructions to carry out or supplement the processes described above,and may include secure information also. Thus, for example, theexpansion memory 474 may be provided as a security module for the mobilecomputing device 450, and may be programmed with instructions thatpermit secure use of the mobile computing device 450. In addition,secure applications may be provided via the SIMM cards, along withadditional information, such as placing identifying information on theSIMM card in a non-hackable manner.

The memory may include, for example, flash memory and/or NVRAM memory(non-volatile random access memory), as discussed below. In someimplementations, instructions are stored in an information carrier. Theinstructions, when executed by one or more processing devices (forexample, processor 452), perform one or more methods, such as thosedescribed above. The instructions can also be stored by one or morestorage devices, such as one or more computer- or machine-readablemediums (for example, the memory 464, the expansion memory 474, ormemory on the processor 452). In some implementations, the instructionscan be received in a propagated signal, for example, over thetransceiver 468 or the external interface 462.

The mobile computing device 450 may communicate wirelessly through thecommunication interface 466, which may include digital signal processingcircuitry where necessary. The communication interface 466 may providefor communications under various modes or protocols, such as GSM voicecalls (Global System for Mobile communications), SMS (Short MessageService), EMS (Enhanced Messaging Service), or MMS messaging (MultimediaMessaging Service), CDMA (code division multiple access), TDMA (timedivision multiple access), PDC (Personal Digital Cellular), WCDMA(Wideband Code Division Multiple Access), CDMA2000, or GPRS (GeneralPacket Radio Service), among others. Such communication may occur, forexample, through the transceiver 468 using a radio-frequency. Inaddition, short-range communication may occur, such as using aBluetooth, WiFi, or other such transceiver. In addition, a GPS (GlobalPositioning System) receiver module 470 may provide additionalnavigation- and location-related wireless data to the mobile computingdevice 450, which may be used as appropriate by applications running onthe mobile computing device 450.

The mobile computing device 450 may also communicate audibly using anaudio codec 460, which may receive spoken information from a user andconvert it to usable digital information. The audio codec 460 maylikewise generate audible sound for a user, such as through a speaker,e.g., in a handset of the mobile computing device 450. Such sound mayinclude sound from voice telephone calls, may include recorded sound(e.g., voice messages, music files, etc.) and may also include soundgenerated by applications operating on the mobile computing device 450.

The mobile computing device 450 may be implemented in a number ofdifferent forms, as shown in the figure. For example, it may beimplemented as a cellular telephone 480. It may also be implemented aspart of a smart-phone 482, personal digital assistant, or other similarmobile device.

Various implementations of the systems and techniques described here canbe realized in digital electronic circuitry, integrated circuitry,specially designed ASICs (application specific integrated circuits),computer hardware, firmware, software, and/or combinations thereof.These various implementations can include implementation in one or morecomputer programs that are executable and/or interpretable on aprogrammable system including at least one programmable processor, whichmay be special or general purpose, coupled to receive data andinstructions from, and to transmit data and instructions to, a storagesystem, at least one input device, and at least one output device.

These computer programs (also known as programs, software, softwareapplications or code) include machine instructions for a programmableprocessor, and can be implemented in a high-level procedural and/orobject-oriented programming language, and/or in assembly/machinelanguage. As used herein, the terms machine-readable medium andcomputer-readable medium refer to any computer program product,apparatus and/or device (e.g., magnetic discs, optical disks, memory,Programmable Logic Devices (PLDs)) used to provide machine instructionsand/or data to a programmable processor, including a machine-readablemedium that receives machine instructions as a machine-readable signal.The term machine-readable signal refers to any signal used to providemachine instructions and/or data to a programmable processor.

To provide for interaction with a user, the systems and techniquesdescribed here can be implemented on a computer having a display device(e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor)for displaying information to the user and a keyboard and a pointingdevice (e.g., a mouse or a trackball) by which the user can provideinput to the computer. Other kinds of devices can be used to provide forinteraction with a user as well; for example, feedback provided to theuser can be any form of sensory feedback (e.g., visual feedback,auditory feedback, or tactile feedback); and input from the user can bereceived in any form, including acoustic, speech, or tactile input.

The systems and techniques described here can be implemented in acomputing system that includes a back end component (e.g., as a dataserver), or that includes a middleware component (e.g., an applicationserver), or that includes a front end component (e.g., a client computerhaving a graphical user interface or a Web browser through which a usercan interact with an implementation of the systems and techniquesdescribed here), or any combination of such back end, middleware, orfront end components. The components of the system can be interconnectedby any form or medium of digital data communication (e.g., acommunication network). Examples of communication networks include alocal area network (LAN), a wide area network (WAN), and the Internet.

The computing system can include clients and servers. A client andserver are generally remote from each other and typically interactthrough a communication network. The relationship of client and serverarises by virtue of computer programs running on the respectivecomputers and having a client-server relationship to each other.

Although a few implementations have been described in detail above,other modifications are possible. For example, while a clientapplication is described as accessing the delegate(s), in otherimplementations the delegate(s) may be employed by other applicationsimplemented by one or more processors, such as an application executingon one or more servers. In addition, the logic flows depicted in thefigures do not require the particular order shown, or sequential order,to achieve desirable results. In addition, other actions may beprovided, or actions may be eliminated, from the described flows, andother components may be added to, or removed from, the describedsystems. Accordingly, other implementations are within the scope of thefollowing claims.

What is claimed is:
 1. (canceled)
 2. A system comprising: a propertyselector of a front end server that is configured to: receive trainingdata that includes previous phrases submitted by digital componentproviders and content selected in response to the submitted phrases; aknowledge graph traverser that is configured to: determine, by accessinga knowledge graph, an entity that is being referred to by each of theprevious phrases submitted by the digital component providers, whereinthe knowledge graph comprises nodes that are each uniquely identifydifferent entities and that are connected by relationships betweenconnected nodes; and determine, by accessing the knowledge graph and foreach entity referred to by each of the previous phrases, relatedentities that are within a threshold distance of a node corresponding tothe entity, wherein the property selector is configured to: train, usingmachine learning, a selection model using the submitted phrases, thecontent selected in response to the submitted phrases, the entitiesreferred to by each previous phrase, the related entities, and therelationship between the entities referred to by each previous phraseand the related entities, and wherein the front end server is configuredto: receive, through a user interface, a phrase submitted by a digitalcomponent provider; provide the phrase as an input to the selectionmodel; receive, from the selection model, a group of phrases that arerelated to the phrase; and update the user interface to present at leasta portion of the group of phrases with programmatic controls that assignone or more of the phrases of the group of phrases as distributioncriteria for digital components of the digital component provider inresponse to activation of the programmatic controls.
 3. The system ofclaim 2, wherein the selection model is configured to identify, bytraversing a portion of the knowledge graph, entities that are relatedto a phrase provided to the selection model.
 4. The system of claim 2,wherein the related entities used to train the selection model arewithin a threshold distance of a node corresponding to the entitiesreferred to by each previous phrase.
 5. The system of claim 2, whereinthe group of phrases received from the selection model comprise aminimum spanning tree among the phrase.
 6. The system of claim 2,wherein: the front end server is configured to receive an activation ofa particular programmatic control of the programmatic controls, theparticular programmatic control assigning a particular phrase of thegroup of phrases as distribution criteria for a particular digitalcomponent of the digital components of the digital component provider,and the property selector is configured to update the selection modelbased on the activation of the particular programmatic control assigningthe particular phrase of the group of phrases as distribution criteriafor the particular digital component of the digital components of thedigital component provider.
 7. The system of claim 2, wherein theselection model is configured to reduce a number of accesses to theknowledge graph when identifying the group of phrases.
 8. The system ofclaim 2, wherein the front end server is configured to: provide thephrase as an input to the selection model by providing the phrase as aninput to the selection model that identifies entities that are relatedto the phrase and identifies the group of phrases that are related tothe phrase.
 9. A computer-implemented method comprising: receivingtraining data that includes previous phrases submitted by digitalcomponent providers and content selected in response to the submittedphrases; determining, by accessing a knowledge graph, an entity that isbeing referred to by each of the previous phrases submitted by thedigital component providers, wherein the knowledge graph comprises nodesthat are each uniquely identify different entities and that areconnected by relationships between connected nodes; determining, byaccessing the knowledge graph and for each entity referred to by each ofthe previous phrases, related entities that are within a thresholddistance of a node corresponding to the entity; training, using machinelearning, a selection model using the submitted phrases, the contentselected in response to the submitted phrases, the entities referred toby each previous phrase, the related entities, and the relationshipbetween the entities referred to by each previous phrase and the relatedentities; receiving, through a user interface, a phrase submitted by adigital component provider; providing the phrase as an input to theselection model; receiving, from the selection model, a group of phrasesthat are related to the phrase; and updating the user interface topresent at least a portion of the group of phrases with programmaticcontrols that assign one or more of the phrases of the group of phrasesas distribution criteria for digital components of the digital componentprovider in response to activation of the programmatic controls.
 10. Themethod of claim 9, wherein the selection model is configured toidentify, by traversing a portion of the knowledge graph, entities thatare related to a phrase provided to the selection model.
 11. The methodof claim 9, wherein the related entities used to train the selectionmodel are within a threshold distance of a node corresponding to theentities referred to by each previous phrase.
 12. The method of claim 9,wherein the group of phrases received from the selection model comprisea minimum spanning tree among the phrase.
 13. The method of claim 9,comprising: receiving an activation of a particular programmatic controlof the programmatic controls, the particular programmatic controlassigning a particular phrase of the group of phrases as distributioncriteria for a particular digital component of the digital components ofthe digital component provider; and updating the selection model basedon the activation of the particular programmatic control assigning theparticular phrase of the group of phrases as distribution criteria forthe particular digital component of the digital components of thedigital component provider.
 14. The method of claim 9, wherein theselection model is configured to reduce a number of accesses to theknowledge graph when identifying the group of phrases.
 15. The method ofclaim 9, wherein: providing the phrase as an input to the selectionmodel comprises providing the phrase as an input to the selection modelthat identifies entities that are related to the phrase and identifiesthe group of phrases that are related to the phrase.
 16. Anon-transitory computer-readable medium storing software comprisinginstructions executable by one or more computers which, upon suchexecution, cause the one or more computers to perform operationscomprising: receiving training data that includes previous phrasessubmitted by digital component providers and content selected inresponse to the submitted phrases; determining, by accessing a knowledgegraph, an entity that is being referred to by each of the previousphrases submitted by the digital component providers, wherein theknowledge graph comprises nodes that are each uniquely identifydifferent entities and that are connected by relationships betweenconnected nodes; determining, by accessing the knowledge graph and foreach entity referred to by each of the previous phrases, relatedentities that are within a threshold distance of a node corresponding tothe entity; training, using machine learning, a selection model usingthe submitted phrases, the content selected in response to the submittedphrases, the entities referred to by each previous phrase, the relatedentities, and the relationship between the entities referred to by eachprevious phrase and the related entities; receiving, through a userinterface, a phrase submitted by a digital component provider; providingthe phrase as an input to the selection model; receiving, from theselection model, a group of phrases that are related to the phrase; andupdating the user interface to present at least a portion of the groupof phrases with programmatic controls that assign one or more of thephrases of the group of phrases as distribution criteria for digitalcomponents of the digital component provider in response to activationof the programmatic controls.
 17. The medium of claim 16, wherein theselection model is configured to identify, by traversing a portion ofthe knowledge graph, entities that are related to a phrase provided tothe selection model.
 18. The medium of claim 16, wherein the relatedentities used to train the selection model are within a thresholddistance of a node corresponding to the entities referred to by eachprevious phrase.
 19. The medium of claim 16, wherein the operationscomprise: receiving an activation of a particular programmatic controlof the programmatic controls, the particular programmatic controlassigning a particular phrase of the group of phrases as distributioncriteria for a particular digital component of the digital components ofthe digital component provider; and updating the selection model basedon the activation of the particular programmatic control assigning theparticular phrase of the group of phrases as distribution criteria forthe particular digital component of the digital components of thedigital component provider.
 20. The medium of claim 16, wherein theselection model is configured to reduce a number of accesses to theknowledge graph when identifying the group of phrases.
 21. The medium ofclaim 16, wherein: providing the phrase as an input to the selectionmodel comprises providing the phrase as an input to the selection modelthat identifies entities that are related to the phrase and identifiesthe group of phrases that are related to the phrase.